The present invention relates generally to the insertion of prewound coils in dynamoelectric machines stator cores and more particularly to a method and apparatus for the insertion of such prewound coils which is readily adapted to various stator core dimensions such as adapting the machine to stator cores of like cross-sectional configuration but varying stack heights.
A number of machines have been devised for inserting prewound coils, as well as, optionally, insulating wedges into stator cores. One such coil placing machine is illustrated in the Hill U.S. Pat. No. 3,324,536. In the Hill device, as in the present invention, preformed coils, for example formed on winding machines of a known type, are placed over appropriate tooling blades or fingers of the placer for subsequent insertion into a stator. Thus coils for all of the poles of the machine to be produced may be placed on the tooling blades and if desired auxiliary or start windings, as well as main windings, may be placed on the blades and inserted into the stator core by but a single axial pass of a stripper along the blades to engage and urge those windings into and partially through the stator core. Various insulating wedges may be inserted into the stator core slots, either to separate windings or to isolate the windings from the stator bore, and such insertion processes may be effected in a single stage operation or in several stages as desired.
The above-mentioned Hill coil placing machine provides for rather rudimentary modifications to accommodate stators of different stack height. To maintain the end turns of the coils at a reasonable minimum when they are positioned in a stator, and of course to accommodate a given coil within the stator for which it is designed, the finger elements or blades should extend about to or just beyond the stator end face and similarly the maximum extension or travel of the stripper through the stator bore should be at most only slightly beyond that necessary to place the windings into the stator. When changing from one stack height to another, the Hill machine provides for the insertion of tubular spacers of a preselected length in conjunction with a certain amount of lost motion in the connection between a stripper actuating ram and the stripper so that the length of the stroke taken by the stripper is appropriate to the particular axial length of the stator being then provided with windings. Similarly, the Hill device provides for adjustment movement of the finger elements or blades and also of so-called wedge guide members by loosening a plurality of screws which hold those fingers and wedge guides in place and this type operation amounts to the individual repositioning or removal of the pertaining blades and guides. While effective, this blade and wedge guide adjustment process was sufficiently time consuming and difficult that an arrangement for simultaneously gripping and moving the blades when the screws were loosened was devised and is disclosed in the Walker et al U.S. Pat. No. 3,402,462.
There have been further attempts to simplify the process of accommodating such a coil placing machine to operate on stators of varying stack height. For example, adjustment of the blades or finger elements by using a centrally tapped blade holder and a threaded tooling shaft, rotatable by a wrench, have been used in several versions with U.S. Pat. No. 3,698,063 being exemplary of such approaches. Typically, the stripper must be removed to allow access by the wrench to make the adjustment.
Also, special machines, for example as illustrated in U.S. Pat. No. 3,829,953, have been designed to achieve multiple adjustments simultaneously. The exemplary patented device employs a chain driven set of variable height control surfaces and an axial stripper drive shaft including a slip clutch connection. This exemplary device varies the height of the stator clamping arms, wedge length, the stroke of the stripper, and the tooling blade axial extent. The approach of this last-mentioned exemplary patented device is not easily adaptable to the vast number of machines already in the field and is rather costly in its implementation.
A substantial improvement in stack height adjusting techniques as thus far discussed is represented by U.S. Pat. No. 4,156,964 assigned to the assignee of the present invention. In this patented device an axially fixed rotatable blade support shaft threadedly engages an axially moveable but rotationally fixed blade holder so that shaft rotation effectively extends or retracts the blades. A ram for actuating the coil stripper is formed of a pair of threaded members so that the stripper may be extended and a pin couples the blade support shaft to the ram and these two members are rotated relative to the stripper and fingers so that the ram extends or retracts relative to the machine the same distance that the fingers extend or retract. On retraction of the stripper, the support shaft is engaged and the stripper actuating ram separates from the stripper. Hence, in the retracted position the stripper rests at a location which is independent of the stack height to which the machine is adjusted. With the stripper returning to a fixed or invariable home position throat room within the coil placer tooling is unduly restricted by the stripper. Also in this patented arrangement the range of stack heights accommodatable is not as great as it might desirably be. Also while this last mentioned patented arrangement may be employed in coil placing machines of the type having certain fingers or blades moveable with the stripper the free ends of the moving blades align with the free ends of the fixed blades only for one particular stack height and to achieve the uniform location of all blade free ends with other stack heights requires the substitution of shorter or longer moving blades on the stripper.